You should be aware that if you only have third party insurance you are not covered if your car is stolen or if you have an acciden that is your fault. Some car insurance companies do not offer third party only options.
If you are involved in an accident with an uninsured driver you should take their details, car registration and model and contact the police immediately.
If you're involved in a road traffic accident that isn't your fault you have the right to claim back losses from the responsible party. This should not impact your no claims bounus as it was not your fault.
Making a claim will not automatically lose all your no claims bonus. Most insurers will relegate you only two years meaning if you had 5 years no claims then you would still have 3 years.
Even if you have had a poor quote from an insurer previously, try them again as sometimes their pricing structures change.